• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.293-298
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• 2003

In this study, tensile adhesive strength(TAS) test was carreid out for evaluated the effects of temperature conditions(-20, -10, 5, 20, 30, $40^{\circ}C$) on the tensile adhesive characteristics about six waterproofing membranes which were commercially used in bridge decks. And, failure appeariences of waterproofing systems in each temperature were investigated and observed the sawing surfaces of waterproofing systems for whether or not damaged of waterproofing membranes. TAS test results were increased when test temperature was decrease in all waterproofing membrane. The type of failure was ductile in $30^{\circ}C$ and $40^{\circ}C$, but brittle failure below $20^{\circ}C$. This results were shown that if temperature above $30^{\circ}C$ is continued for a long time, waterproofing material will be damaged by softening and a part of membranes were damaged by hot aggregate in SMA. So we will consider the type of asphalt for choice of the waterproofing membranes.

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.52-59
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• 2000

Flexural fracture characteristics of newly-developed Grid-type carbon fiber plastics in the deteriorated reinforced concrete structures were investigated by the four-points fracture test to verify the strengthening effects in the beam specimens. Results showed that initial cracks appeared in the boundary layers of fibers embedded in the newly-placed mortar concrete slowly progressed to the direction of supports and showed fracture of fiber plastics and brittle failure of concrete in compression in sequence after the yielding of steel reinforcement. Accordingly the reasonable area of Grid-type carbon-fiber plastics in the strengthening design of deteriorated RC structures should be limited and given based on the ultimate strength design method to avoid the brittle failure of concrete structures.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.2
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• pp.62-69
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• 2000

In this paper, we propose two Buckley-James type nonparametric estimators for entropy of lifetimes under random censorship model. We investigate the small sample behaviors of the proposed estimators when the underlying distribution has decreasing failure rate, constant failure rate, and increasing failure rate. Also some examples are illustrated for analysing data.

• Journal of the military operations research society of Korea
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• v.16 no.2
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• pp.135-150
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• 1990

This paper classifies faults into three types : simple, degenerated, and regenerated faults. This paper also deals with the characteristics of each type of fault to determine the software reliability based on the assumption; i. e., a system consisting of several subsystems (modules) which may be debugged simultaneously. For each type of fault, several formulas are developed to obtain the failure rate and the expected number of failures found during debugging. A model is developed based on the formulas of the failure rate and the expected number of failures to decide the optimal release time of a new software: minimizing the total cost with constraints restricting to the failure rate of each module in the software. By using this model, optimal release times are found for some cases; the eliminated faults are assumed simple faults only, regenerated faults only, simple and degenerated faults, and so on.

• Journal of the Korean Data and Information Science Society
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• v.23 no.4
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• pp.843-850
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• 2012

The inferences of data obtained from periodic inspection and type I censoring for the three step stress accelerated life test are studied in this paper. The failure rate function that a log-quadratic relation of stress and the tampered failure rate model are considered under the exponential distribution. The optimal stress change times which minimize the asymptotic variance of maximum likelihood estimators of parameters is determined and the maximum likelihood estimators of the model parameters are estimated. A numerical example will be given to illustrate the proposed inferential procedures.

• KIEE International Transactions on Power Engineering
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• v.5A no.3
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• pp.286-292
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• 2005

As the power industry moves towards open competition, there has been a call for methodology to evaluate power system reliability by using composite interruption cost. This paper presents algorithms to evaluate the interruption cost of distribution power systems by taking into consideration the failure source and the composite customer interruption cost. From the consumer's standpoint, the composite customer interruption cost is considered as the most valuable index to estimate the reliability of a power distribution system. This paper presents new algorithms that consider the load by customer type and failure probability by distribution facilities while calculating the amount of unserved energy by customer type. Finally, evaluation results of unserved energy and system interruption cost based on composite customer interruption cost are shown in detail.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.19-26
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• 2005

There are three reasoning method in fault diagnosis process. The shallow reasoning is based on the experiential knowledge and deep reasoning is based on physical model. Hybrid reasoning is mixing two type reasoning. This study describes about fault train embodiment of screw type air compressor that is used widely in industrial facilities by using various experimental method and shallow reasoning. We investigate macroscopic failure cause of air compressor through naked eye observation and then microscopic failure cause by various experimental method. We composed fault train with fault knowledge based on empirical data and scientific data that is acquired through several experiments. It is possible to analysis system reliability and failure rate with these fault train.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.301-305
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• 2005

This paper introduces a novel technique to detect and isolate the failures of multiple actuators connected to a system. Failure of actuator considered in this study could be any type of erroneous input that is different from commanded one. The interaction matrix technique allows the development of input-output equations that are only influenced by one target input. These input-output equations serve as an effective toot to monitor the integrity of each actuator regardless of the status of the other actuators. The method is capable of real-time actuator failure detection and isolation under any type of input excitation. The laboratory experiment using 8-bay NASA truss structure verifies the feasibility of the proposed method.

• Journal of the Korean Geotechnical Society
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• v.34 no.10
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• pp.61-74
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• 2018

In this study, the pull-out behavior of tunnel type anchorage of suspension bridges was analyzed based on results from laboratory size model tests and numerical analysis. Tunnel type anchorage has found its applications occasionally in both domestic and oversea projects, therefore design method including failure mode and safety factor is yet to be clearly established. In an attempt to improve the design method, scaled model tests were conducted by employing simplified shapes and structure of the Ulsan grand bridge's anchorage which was the first case history of its like in Korea. In the model tests, the anchorage body and the surrounding rocks were made by using gypsum mixture. The pull-out behavior was investigated under plane strain conditions. The results of the model tests showed that the tunnel type anchorage underwent wedge shape failure. For the verification of the model tests, numerical analysis was carried out using ABAQUS, a finite element analysis program. The failure behavior predicted by numerical analysis was consistent with that by the model tests. The result of numerical analysis also showed that the effect of Poisson's ratio was negligible, and that a plugging type failure mode could occur only when the strength of the surrounding rocks was 10 times larger than that of anchorage body.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.731-738
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• 2002

To understand failure behavior of pipe thinned by flow accelerated corrosion, in this study, the pipe failure tests were performed on 102mm-Sch.80 carbon steel pipe with various local wall thinning shapes, and the failure mode, load carrying capacity, and deformability were investigated. The tests were conducted under loading conditions of 4-points bending and internal pressure. The experimental results showed that the failure mode of thinned pipe depended on magnitude of internal pressure and thinning length as well as loading direction and thinning depth and angle. The variation in load carrying capacity and deformability of thinned pipe with thinning length was determined by stress type appled to the thinning area and circumferential thinning angle. Also, the effect of internal pressure on failure behavior was dependent on failure mode of thinned pipe, and it promoted crack occurrence and mitigated local buckling at thinned area.